In previous studies we have described various aspects of adenylate cyclase, its dispersion, chromatographic behavior, kinetics with respect to metal and metal-ATP, stimulation and inhibition by adenosine, and the influence on its assay of nucleotide pyrophosphatase and components of ATP-regenerating systems. We have developed improved methods for assaying activity and an enzymatic procedure for preparing labeled substrate. Our immediate objectives in the proposed studies are to complete current studies on the effect of NAD to enhance fluoride-stimulated adenylate cyclase activity and of vanadate to stimulate the enzyme. We will otherwise be devoting energy to: 1. establishing relationships between phosphorylation and dephosphorylation of membrane protein and cyclase activity; 2. establishing conditions for reproducible effects of oxidizing or reducing environments on enzyme activity; and 3. applying the chromatographic systems we have developed to a larger scale purification of adenylate cyclase.